Reversible contact bridge arrangement for electrical switches

ABSTRACT

A contact bridge arrangement for a rotary type stepping switch having a contact bridge arranged on a switching arm which is generally disposed parallel to two parallel contact paths, a portion of such paths consisting at least partly of individual contacts. The contact bridge has a set of bridging contacts on one side, with a set of break contacts being located on the opposite side whereby the contact bridge is readily reversible on the switching arm without dismantling the switch so that at choice either the bridging contacts or the break contacts will be in position to collaborate with and operatively engage the contact paths.

United States Patent [151 3,689,714 Walz Sept. 5, 1972 [54] REVERSIBLE CONTACT BRIDGE 1,815,577 7/1931 Nenzel ..200/ 16 D ARRANGEMENT FOR ELECTRICAL 2,988,606 6/1961 Allison ..200/11 A SWITCHES 3,061,692 10/ 1962 Fowler et a] ..200/ 16 D 3,352,979 11/1967 Grayson etal ..200/11 A [72] Invent Mmfred Walz Musberg Germany 3,502,824 3/1970 Bonacquisti ..200/16 D [73] Assignee: EBE Elektro Rau-Elemente GmbH,

Stetten/Filder, Germany Primary Examiner-J. R. Scott Att0meyGeorge F. Dvorak, Stephen T. Skrydlak [22] Filed. Dec. 14, 1970 and Marden S. Gordon; [2]] Appl. No.: 97,596

[57] ABSTRACT [30] Foreign Application Priority Data A contact bridge arrangement for a rotary type stepping switch having a contact bridge arranged on a 1969 Germany 19 64 580'8 switching arm which is generally disposed parallel to two parallel contact paths, a portion of such paths "200/11 232 2553 2 consisting at least partly of individual contacts. The [58] Field A 16 D B6 166 contact bridge has a set of bridging contacts on one 200/; 66 J side, with a set of break contacts being located on the opposite side whereby the contact bridge is readily reversible on the switching arm without dismantling [56], References cued the switch so that at choice either the bridging con- UNITED STATES PATENTS tacts or the break contacts will be in position to collaborate with and operatively engage the contact 2,706,760 4/1955 Mucher ..200/166 J X paths 2,549,998 4/1951 Allison ..200/11 A 15 Claims, 4 Drawing Figures T N 27 L REVERSIBLE CONTACT BRIDGE ARRANGEMENT FOR ELECTRICAL SWITCHES SCOPE OF THE INVENTION It is an object of the invention to provide a contact bridge arrangement of the type hereinafter described in which the contact bridge may be reversed in a simple manner without having to dismantle the switch. Furthermore, the contact bridge arrangement according to the invention may be economically manufactured and easily exchanged.

It is a further object of the invention to provide a contact bridge of the type hereinbefore described in which the bridging contacts and the break contacts are mounted on opposite sides of the contact bridge, wherein contact bridge is adapted to be reversed through 180 about an axis extending perpendicularly to the contact paths and parallel to the contact path plane. Thus, compared with the known contact bridge arrangement, the contact bridge according to the invention is reversed, in the case of a rotary stepping switch, about an axis which extends perpendicularly to the axis of the switch. This makes it possible to reverse the contact bridge easily from the position for breaking switching into the position for bridging switching or vice versa.

Although it is already known from British Pat. No. 634,171 to providecontacts, connected by spring arms, on opposite sides of a switching arm for making an electrical connection between a fixed slip ring on one side of the switching arm and fixed individual contacts on the other side, the reversibility of the detachably mounted contacts is not intended in this case and would not be meaningful with the known switch. Furthermore, Eastern German Pat. No. 16,502 describes a reversible contact element but this has not the object of providing at choice bridging or nonbridging switching and has merely the object of facilitating the replacement of worn contacts.

In a preferred embodiment of the invention, the contact bridge is adapted to be pulled off the switching arm in the direction of the reversing axis and may be refitted after rotation through 180 about this axis. In this manner, the contact bridge may be removed simply from its operating position facilitating not only its reversal but also its replacement by another contact bridge.

In a particularly preferred embodiment of the invention, the contact bridge is a U-shaped spring element, the legs of which carry the contacts. Preferably, the legs of the spring are adapted to fit into recesses provided on both sides of the switching arm. In this manner, a correct guide is provided for the displacement of the contact bridge.

The web or base of the U-shaped spring element is preferably fitted into a recess provided in the edge of the switching arm so that there are no radially projecting parts of the contact bridge in the case of a rotary stepping switch.

According to yet another embodiment of the invention, the firm mounting of the contact bridge on the switching arm is ensured in that the ends of the legs of the spring element have inwardly projecting retaining beads which engage into corresponding recesses of the switching arm.

In order to facilitate the fitting of the contact bridge, the switching arm may be provided on the side receiving the spring element with chamfers for the two ends of the legs. The fitting of the contact bridge may be further facilitated by recesses provided on both sides of the switching arm on the side facing the spring element.

In a particularly simple and economical embodiment of the invention, the contacts are punched out of the spring sheet element.

The contact bridge arrangement according to the invention may be used particularly efficiently by providing two facing, contact paths, parallel to both sides of the switching arm and consisting at least partially of individual contacts. This embodiment utilizes in an advantageous manner the fact that contacts are located on both sides of the switching arm of which in the basic construction always only one pair of contacts is in operation at any given time.

When the contact bridge arrangement according to the invention is used in a stepping switch with one continuous contact path and one contact path consisting of individual contacts, preferably two identical contacts are formed on both sides of the switching arm above the continuous contact path. On the other side of the switching arm, one bridging or break contact is preferably formed above the contact path consisting of individual contacts.

Preferably, the two contacts associated with each contact path are diagonally offset relative to each other. In this manner, the elastic arms of each contact may extend substantially over the radial length of the contact bridge, thereby achieving a favorable spring effect.

Preferably, the contacts are mounted resiliently on the bridge to produce a contact force. It is, however, also possible to provide the contacts firmly on the bridge and to provide a spring bias for the switching arm perpendicularly to the plane of the contacts to produce this contact force.

According to yet another embodiment of the invention, the construction may be such that only on one side of the contact bridge there are provided contacts connecting the contacts of the associated contact paths. Although this construction no longer permits the reversal of the bridge, it enables a very simple exchange of the contact bridge to be effected. Preferably, different contact bridges are available for one and the same switch and these may be fitted as required to the contact bridge carrier, referred to as the switching arm.

DETAILED DESCRIPTION OF THE DRAWINGS In the following the invention will be described, by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a cross-section of a contact bridge arrangement according to the invention, perpendicularly to the plane of the contact path and to the direction of movement of the switching arm;

FIG. 2 is a plan view of the arrangement of FIG. 1;

FIG. 3 is an end elevation viewed from the line III- III in FIG. 1;

FIG. 4 is a cross-section along the line IVIV in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing shows a contact bridge arrangement according to the invention in its preferred application in conjunction with a rotary stepping switch. The rotary switch has a circular contact plate 28 on which a switching arm 14 is rotatably mounted by means of a circular support disk 29 and screws 27. The axis of rotation is shown at 30 in FIGS. 2 and 4.

On the contact plate 28, there are two concentric contact paths 11, 12, of which the outer path 11 consists of individual contacts 13 while the inner contact path 12 is formed by a continuous metal strip. However, it is also possible for the inner contact path to consist of individual contacts or segments.

To enable the individual contacts 13 to be switched at choice in a bridging or in a breaking manner, the switching arm 14 has a contact bridge which is provided on opposite sides of the switching arm 14 with bridging contacts 15 and break contacts 16, respectively. These contacts are located on the radius of the contact path 11.

In addition thereto, the contact bridge 17 has further contacts 19, 20 on opposite sides on the radius of the contact path 12.

The contact bridge is formed by a U-shaped spring plate which is adapted to be fitted to the switching arm 14 so that the web of the U extends parallel to the axis of rotation and the legs parallel to the radius of the rotary switch.

According to the invention the contact bridge 17 may be detached from the switching arm 14 in the radial direction and fitted thereon in the same sense. The contact bridge 17 is symmetrical so that it can be fitted on to the switching arm 14 after rotation about its axis 18 through 180.

In the preferred embodiment shown, the contacts l5, 16, 19, 20, are embossed by punching from the material of the spring plate. In view of the diagonal arrangement of the contacts, shown particularly clearly in FIG. 3, the arms of the individual contacts may be so long that they act after the manner of springs, thereby eliminating the necessity for providing special contact springs.

In order to secure the contact bridge 17 reliably on the switching arm 14, the switching arm 14 has on both sides recesses 21 and on the outside a recess 22 and the contact bridge 17 is constructed to fit into these recesses. Furthermore, the legs of the spring plate 17 acting as contact bridge have at their ends retaining beads 23 which engage resiliently into corresponding retaining recesses 24 provided in the switching arm 14.

Chamfers 25 are provided on the outside of the switching arm in the region of the contact bridge and enable the legs of the contact bridge to be resiliently fitted. To facilitate the fitting recesses 26 are provided on both sides of the switching arm 14, adapted to receive the contact bridge 17. This provides a positive guide for the contact bridge while the legs slide along the chamfers 25. This construction substantially facilitates the reversing and exchange of the contact bridge.

A particularly preferred embodiment, not represented in the drawing, comprises a contact plate with two contact paths on the side of the switching arm 14 remote from the contact plate 28, wherein the contact paths of the second contact plate extend parallel to the contact paths 11, 12. In this case, in the embodiment shown in the drawing, also the contacts l6, 19 could be used. Should this be desired, the contacts 15, 20 and 16, 19, respectively, provided on both sides of the switching arm, could be insulated against each other.

The switching arm may also be constructed as a rotor. It is only essential that it carries the contact bridge and permits its movement along the contact paths.

I claim:

1. A rotary electric switch comprising a rotatably mounted switching arm of insulating material, a contact plate of insulating material disposed parallel to the switching arm and mountably supporting at least two concentrically disposed electrical contact paths thereon, at least one of the contact paths consisting at least partly of individual spaced stationary contacts, a contact bridge arrangement detachably mounted on the switching arm for rotary movement therewith, the contact bridge having contacts thereon adapted to slideably engage and cooperate with the contact paths to connect the individual contacts of the contact paths in a selected predetermined manner, the contact bridge contacts including a set of bridging contacts and a set of break contacts with respect to the contact paths, the bridging contacts being disposed on one side of the switching arm with the break contacts being disposed on the opposite side of the switching arm, the contact bridge arrangement adapted for removal from the switching arm and reversed through an angle of about an axis extending in the radial direction so as to select the side of the contact bridge and associated bridging or break contacts to be brought into operative sliding engagement with the contact paths.

2. The rotary electric switch of claim 1 wherein the contact bridge arrangement is a resilient U-shaped spring plate having substantially parallel leg portions and an interconnecting web portion, the plate being detachably supported on the switching arm by the clamping action of the resilient leg portions on the switching arm, the plate adapted to be detached from the switching arm in the radial direction, rotated 180 about the longitudinal axis of the plate, and again mounted on the switching arm whereby a new set of contacts are now disposed for slideably engaging the contact paths.

3. The rotary electric switch of claim 2 wherein recesses are provided on opposite sides of the switching arm, and the leg portions of the U-shaped spring plate are adapted to engage into the recesses so as to position the spring plate on the switching arm.

4. The rotary electric switch of claim 2, wherein a recess is provided in the outermost edge of the switching arm, and the web portion of the U-shaped spring plate is received in the edge recess so that no portion of the contact bridge projects from the outermost end of the switching arm. I

5. The rotary electric switch of claim 2 wherein the outermost edge of the switching arm has chamfers adapted to co-operate with each of the free ends of the leg portions of the U-shaped spring plate to facilitate the attachment of the contact bridge arrangement onto the switching arm.

6. The rotary electric switch of claim 2 wherein the bridging and break contacts on the contact bridge arrangement are integral portions of the leg portions of the spring plate produced by being punched out of the spring plate.

7. The rotary electric switch of claim 1 wherein the two contact paths consist of one continuous uninterrupted contact path and one contact path consisting of individual spaced stationary contacts, the contact bridge arrangement includes an identical contact positioned on each side of the switching arm directly above the continuous contact path, and a bridging contact on one side of the switching arm and a break contact on the other side of the switching arm, respectively, directly above the contact path of individually spaced contacts.

8. The rotary electric switch of claim 1 wherein the contact of each set of contacts which are disposed to engage the same contact path are circumferentially offset relative to each other.

9. A rotary electric switch comprising:

a stationary contact mounting plate of insulating material;

a rotatable switching arm of insulating material disposed parallel to the mounting plate and spaced therefrom, the switch arm rotatable relative to the contact mounting plate about an axis generally perpendicular to the mounting plate, the switching arm having a top side surface and a bottom side surface with the bottom surface being in spaced juxtaposition with said mounting plate;

a first contact path defined on said mounting plate by a plurality of individual spaced stationary first contacts mounted on said mounting plate about the circumference of an approximate circle having its center common with said axis of rotation of said switching arm;

a second contact path defined on said mounting plate concentric to said first contact path and radially spaced therefrom;

a Ushaped contact bridge arrangement detachably mounted on said switching arm for rotation therewith, said contact bridge including two legs interconnected at one end by a web portion, one leg of said bridge being received on the top surface of the switching arm with the other leg of said bridge being received on the bottom surface of said switching arm, said contact bridge being removable from said switching arm, rotated 180 about its longitudinal axis, and mounted in this reversed position on said switching arm so that said one bridge leg would then be received on said bottom surface of said switching arm with said other bridge leg then being received on said top surface of said switching arm thereby permitting the selective choosing of the particular bridge leg to be received by said bottom surface of said switching arm for juxtapositioning with said contact paths;

said one bridge leg having electrically connected first and second contacts formed thereon arranged for sliding engagement with said first and second contact paths respectively when said one bridge leg is placed in juxtaposition thereto on said switching arm, said first contact being smaller in size than the spacing between adjacent said first individually spaced stationary contacts on said mounting plate so that no bridging occurs between adjacent stationary contacts when said one bridge leg first contact is moved therebetween;

said other bridge leg having electrically connected third and fourth contacts thereon arranged for sliding engagement with said first and second contact paths respectively when said other bridge leg is positioned on said switching arm in juxtaposition with said contact paths on said mounting plate, said other bridge leg third contact being larger in size than the spacing between adjacent said first individually spaced stationary contacts on said mounting plate so that bridging occurs between adjacent individually spaced stationary contacts when said third contact is slideably moved therebetween;

said contact bridge being selectively disposed on said switching arm with said one leg in juxtaposition with said mounting plate so as to bring by choice individual of said first individually spaced stationary contacts into electrical connection with said second contact path by said first and second contacts when said one bridge leg is positioned on said switching arm in juxtaposition with said mounting plate, and by reversing said contact bridge on said switching arm so that said other leg is in juxtaposition with said mounting plate, to bridge by choice adjacent said first individually spaced contacts on said mounting plate thereby electrically interconnecting such adjacent contacts by the bridging of said third contact on said other bridge leg and placing the bridged adjacent contacts in electrical connection with said second contact path by said fourth contact.

10. The rotary electric switch of claim 9 wherein a plurality of circumferally spaced radially extending recesses are formed in opposite sides of said switching arm, and said leg portions of said contact bridge resiliently detachably engage into one of said recesses for positioning the contact bridge on the switching arm.

11. The rotary electric switch of claim 9 wherein a plurality of circumferally spaced recesses are formed in the outermost edge of said switching arm, said web portion of said contact bridge being fully received in said recess so that no portion of the contact bridge projects radially outwardly from said switching arm.

12. The rotary electric switch of claim 9 wherein the outermost edges of the switching arm have chamfers formed therein adapted to co-operate with the free end of each bridge leg to facilitate the selective attachment of the contact bridge onto the switching arm.

13. The rotary electric switch of claim 9 wherein said first, second, third, and fourth contacts on said contact bridge are defined by punching out integral portions of each bridge leg.

14. The rotary electric switch of claim 9 wherein said first and third contacts on said contact bridge are positioned on opposite sides of said switching arm directly above said first contact path, and said second and fourth contacts contact bridge are positioned on opposite sides of said switching arm directly above said second path.

15. The rotary electric switch of claim 9 wherein said first contact is circumferentially offset relative to said third contact, and said second contact is circumferentially offset relative to said fourth contact. 

1. A rotary electric switch comprising a rotatably mounted switching arm of insulating material, a contact plate of insulating material disposed parallel to the switching arm and mountably supporting at least two concentrically disposed electrical contact paths thereon, at least one of the contact paths consisting at least partly of individual spaced stationary contacts, a contact bridge arrangement detachably mounted on the switching arm for rotary movement therewith, the contact bridge having contacts thereon adapted to slideably engage and cooperate with the contact paths to connect the individual contacts of the contact paths in a selEcted predetermined manner, the contact bridge contacts including a set of bridging contacts and a set of break contacts with respect to the contact paths, the bridging contacts being disposed on one side of the switching arm with the break contacts being disposed on the opposite side of the switching arm, the contact bridge arrangement adapted for removal from the switching arm and reversed through an angle of 180* about an axis extending in the radial direction so as to select the side of the contact bridge and associated bridging or break contacts to be brought into operative sliding engagement with the contact paths.
 2. The rotary electric switch of claim 1 wherein the contact bridge arrangement is a resilient U-shaped spring plate having substantially parallel leg portions and an interconnecting web portion, the plate being detachably supported on the switching arm by the clamping action of the resilient leg portions on the switching arm, the plate adapted to be detached from the switching arm in the radial direction, rotated 180* about the longitudinal axis of the plate, and again mounted on the switching arm whereby a new set of contacts are now disposed for slideably engaging the contact paths.
 3. The rotary electric switch of claim 2 wherein recesses are provided on opposite sides of the switching arm, and the leg portions of the U-shaped spring plate are adapted to engage into the recesses so as to position the spring plate on the switching arm.
 4. The rotary electric switch of claim 2, wherein a recess is provided in the outermost edge of the switching arm, and the web portion of the U-shaped spring plate is received in the edge recess so that no portion of the contact bridge projects from the outermost end of the switching arm.
 5. The rotary electric switch of claim 2 wherein the outermost edge of the switching arm has chamfers adapted to co-operate with each of the free ends of the leg portions of the U-shaped spring plate to facilitate the attachment of the contact bridge arrangement onto the switching arm.
 6. The rotary electric switch of claim 2 wherein the bridging and break contacts on the contact bridge arrangement are integral portions of the leg portions of the spring plate produced by being punched out of the spring plate.
 7. The rotary electric switch of claim 1 wherein the two contact paths consist of one continuous uninterrupted contact path and one contact path consisting of individual spaced stationary contacts, the contact bridge arrangement includes an identical contact positioned on each side of the switching arm directly above the continuous contact path, and a bridging contact on one side of the switching arm and a break contact on the other side of the switching arm, respectively, directly above the contact path of individually spaced contacts.
 8. The rotary electric switch of claim 1 wherein the contact of each set of contacts which are disposed to engage the same contact path are circumferentially offset relative to each other.
 9. A rotary electric switch comprising: a stationary contact mounting plate of insulating material; a rotatable switching arm of insulating material disposed parallel to the mounting plate and spaced therefrom, the switch arm rotatable relative to the contact mounting plate about an axis generally perpendicular to the mounting plate, the switching arm having a top side surface and a bottom side surface with the bottom surface being in spaced juxtaposition with said mounting plate; a first contact path defined on said mounting plate by a plurality of individual spaced stationary first contacts mounted on said mounting plate about the circumference of an approximate circle having its center common with said axis of rotation of said switching arm; a second contact path defined on said mounting plate concentric to said first contact path and radially spaced therefrom; a U-shaped contact bridge arrangement detachably mounted on said switching arm for rotation therewith, said contact bridge including two legs interconnected at one end by a web portion, one leg of said bridge being received on the top surface of the switching arm with the other leg of said bridge being received on the bottom surface of said switching arm, said contact bridge being removable from said switching arm, rotated 180* about its longitudinal axis, and mounted in this reversed position on said switching arm so that said one bridge leg would then be received on said bottom surface of said switching arm with said other bridge leg then being received on said top surface of said switching arm thereby permitting the selective choosing of the particular bridge leg to be received by said bottom surface of said switching arm for juxtapositioning with said contact paths; said one bridge leg having electrically connected first and second contacts formed thereon arranged for sliding engagement with said first and second contact paths respectively when said one bridge leg is placed in juxtaposition thereto on said switching arm, said first contact being smaller in size than the spacing between adjacent said first individually spaced stationary contacts on said mounting plate so that no bridging occurs between adjacent stationary contacts when said one bridge leg first contact is moved therebetween; said other bridge leg having electrically connected third and fourth contacts thereon arranged for sliding engagement with said first and second contact paths respectively when said other bridge leg is positioned on said switching arm in juxtaposition with said contact paths on said mounting plate, said other bridge leg third contact being larger in size than the spacing between adjacent said first individually spaced stationary contacts on said mounting plate so that bridging occurs between adjacent individually spaced stationary contacts when said third contact is slideably moved therebetween; said contact bridge being selectively disposed on said switching arm with said one leg in juxtaposition with said mounting plate so as to bring by choice individual of said first individually spaced stationary contacts into electrical connection with said second contact path by said first and second contacts when said one bridge leg is positioned on said switching arm in juxtaposition with said mounting plate, and by reversing said contact bridge on said switching arm so that said other leg is in juxtaposition with said mounting plate, to bridge by choice adjacent said first individually spaced contacts on said mounting plate thereby electrically interconnecting such adjacent contacts by the bridging of said third contact on said other bridge leg and placing the bridged adjacent contacts in electrical connection with said second contact path by said fourth contact.
 10. The rotary electric switch of claim 9 wherein a plurality of circumferally spaced radially extending recesses are formed in opposite sides of said switching arm, and said leg portions of said contact bridge resiliently detachably engage into one of said recesses for positioning the contact bridge on the switching arm.
 11. The rotary electric switch of claim 9 wherein a plurality of circumferally spaced recesses are formed in the outermost edge of said switching arm, said web portion of said contact bridge being fully received in said recess so that no portion of the contact bridge projects radially outwardly from said switching arm.
 12. The rotary electric switch of claim 9 wherein the outermost edges of the switching arm have chamfers formed therein adapted to co-operate with the free end of each bridge leg to facilitate the selective attachment of the contact bridge onto the switching arm.
 13. The rotary electric switch of claim 9 wherein said first, second, third, and fourth contacts on said contact bridge are defined by punching out integral portions of each bridge leg.
 14. The rotary electric switch of claim 9 wherein said first and third contacts on said contacT bridge are positioned on opposite sides of said switching arm directly above said first contact path, and said second and fourth contacts contact bridge are positioned on opposite sides of said switching arm directly above said second path.
 15. The rotary electric switch of claim 9 wherein said first contact is circumferentially offset relative to said third contact, and said second contact is circumferentially offset relative to said fourth contact. 